Reinforced wire brush



Aug. 11, 1953 G. H. SWART REINFORCED WIRE BRUSH Filed May 4, 1949 INVENTOR Gilbert H- Swart ATTORNEYS Patented Aug. 11, 1953 REINFORCED WIRE BRUSH Gilbert H. Swart, Akron, Ohio, assignor to The General Tire and Rubber Company, Akron, Ohio, a corporation of Ohio Application May 4, 1949, Serial No. 91,280

5 Claims.

This invention relates to improvements in metal brushes such as are used for polishing and cleaning of metal and other articles. It particularly relates to wire brushes having improved operating characteristics and to a method of preparing such brushes.

Enormous quantities of wire brushes are utilized for the cleaning and polishing of metal articles, castings and the like. These brushes have much shorter life than would be expected because of normal wear on the cutting or cleaning edges of the bristles. They are frequently subjected to moisture which causes rusting and deterioration of the wires. When they are subjected to extra hard usage or to considerable pressure in the polishing or cleaning operation, the flexing of the wires frequently becomes so severe that a great deal of filament breakage may occur. It is for these reasons it has been thought that an improvement might result if the bristles were completely embedded in a rubber compound. However, it is exceedingly difficult, if not impossible, to embed bristles in a rubber compound for the reason that in any molding operation the flow of rubber tends to greatly distort the bristle pattern, with the result that the brush may have an uneven cutting path. Furthermore, rubber compounds usually contain sulfur that reacts with iron wire and they have very substantial abrasion resistance, which is frequently substantially greater than the abrasion resistance of steel. With such a high abrasion resistance the bristles can wear off below the surface of the rubber and the desirable characteristics of a wire brush are not obtained.

This even though the bristles may be protected from the elements and give suificient rigidity so that their life is greatly enhanced.

It is an object of the present invention to provide a wire brush in which the wire bristles are substantially completely embedded and are reinforced against fiexure by a composition which has substantial strength, which protects them from the elements and from most corrosive fluids, but which has a sufficiently lower abrasion resistance than does metal so that it does not noticeably interfere with the operations for which the ends of wire bristles are especially suited.

It is another object of the present invention to provide a wire brush having the bristles reinforced and protected from the elements by a composition which is not susceptible to deterioration by grease and other liquids with which such brushes may come in contact, and which while Ill) 2 having relatively high strength has sufllclently lower abrasion resistance than metal to wear sufliciently to expose the cutting edges of the wire so that the wire bristles take substantially all of the abrasion in the operation of the brush.

Other objects will be apparent from the following description of the invention as illustrated in the accompanying drawing, in which:

Figure 1 is a plan view of a mold containing a wire brush embodying the present invention and suitable for the final step in the manufacture of one form of wire brush (rotary) embodying the present invention; I

Fig.2 is a sectional view on the line 22 of Fig. l;

Fig. 3 is a plan view of a portion of a brush embodying the present invention; and

Fig. 4 is a sectional view on the line 4-4 of Fig. 2.

I have found that the above objects are accomplished by immersing the entire bristle portion of the conventional wire brush in a fluid comprising a polymerizable or copolymerizable polyester or condensation polymer and capable of setting or changing by molecular growth from the liquid to the solid state and then causing the solidification while the bristles are substantially completely embedded therein. The wire brush body is preferably incorporated in a suitable mold and a fluid polyester mixture or condensation polymer of the type capable of solidification by molecular growth maybe added to the mold in sufficient volume to completely envelop the bristle portions of the brush. It is polymerized or solidified in contact with the bristles to embed them in a solid matrix.

I have found that the solids polymerized from a mixture comprising an unsaturated polyester and a copolymerizable monoolefinic compound, when solidified in situ throughout the bristle portions of the wire brushes, greatly improve the operation of such brushes. These solidified condensation polymers are exceptional in that they have almost no abrasion resistance and yet have relatively high strength and resistance to deterioration against chemical attack in various fluids. They need contain no sulfur or chemicals thatreact with metal and because of their low abrasion resistance they wear down much more readily than do the wire bristles, with the result that the ends of the wire are exposed and the operation of the wire brushes is not adversely interfered with. They enhance the cutting and cleaning operations of the wire brushes for the reason that they greatly stiffen the wire bristles and prevent their deterioration by flexing.

The condensation polymers which are rubbery are particularly effective and are preferred. The copolymers of linear polyesters containing unsaturated linkages with mono-olefinic compounds, such as styrene, methyl methacrylate, methyl acrylate and acrylonitrile, are exceptional. Th'ese' linear polyesters 'usuall'ycomprise a polyhydric alcohol, preferably a dihydric alcohol such as ethylene glycol, diand tri-ethylene' glycols, etc., and a mixture of any one'ormore saturated and any one or more unsaturated dibasic acids.

The saturated dibasic acid is-preferably' any dicarboxylic acid of a sufficient number of carbon atoms to prevent formation with the dihydric alcohols of a five, six or seven-numbered ring, and usually has at least four carbon'atomsi Examples of such acids are adipic acid, sebacic acid,-phthalicacid,- terphthalic acid'-,-etc., a1- though any-dicarboxylicacid-may be used pro viding' thealcohols a-re'chosen to prevent ring formation. The saturated acids generally comprisea-- maj or proportion of the 1 acidic material. The unsaturated dibasic -acids; of which maleic and fumaric acids are examples, comprise gen erally a-minor portion of the composition and are present merelyto-provide crosslinking points for polymerization with a-suitable mono-olefinic compound, such-- as styrene,- etc; The amount of unsaturation has a--di-rect bearing-on the shrinkage during the casting process, hence it is desirable to have theunsaturated-acid as low as compatibility with styrene or mono-olefinic com ponent' permits. a The -mono-olefinic component which copolymerizes with thepolyesters of the preferred type to crosslink-the fluid polyester and assist in its conversion to the solid state may be any. polymerizable mono-olefiniccompound or any mono-olefiriic compound copolymerizabl with maleic anh'yd'rid. Examples of such are the acrylic and -methacrylit': esters and nitriles, styrenes; polymerizable' nuclearly substituted styrenes; including allthe chlorostyrenes, the corresponding alpha-alkylstyrenes, etc.

The'polyester components are usually prepared by first condensinga'polyhydric alcohol and a mixture of dibasic acids, or'th'eir anhydrides, to form'a liquid-to viscouspolyester which is pref erably largelycf "linear nature. This polyester is generally condensed by'stirring-the mixture of reactants whil'e heated' 'to' boiling until the boilingp'oi'nt of the reactants becorneswell over" 200 C, where 'it is evident that most of the'water formed by'the-"condensation reaction isremoved as soon as it is formed; Th'e 'container inwhich the" esterifi'cationreaction generally occurs is fitted-with a suitable reflux condenser which operates at-a sufiiciently high temperature to 4 dihydric alcohol or by the use of suitable unsaturated hydroxy aliphatic acids.

The hardness of the plastic composition may be determined by the relative proportion of monoolefinic monomer that is mixed with the polyester and about equal proportions, by weight, or from 30 parts of polyester to '70 parts of styrene or mono-'olefin'ic'monomer} t'o' 3'O'-'parts of styrene and7o par'tsof polyestera're quite satisfactory. The rubber properties are enhanced by increasing the amount of polyester, and the hardness is enhanced by increasing the proportion of styrene or mono-olefinic component. Generally a higher molar-percentage of 'polyester than of styrene or mono-olefinic compound is preferred so that a rubbery typeof material is had. The amount of shrinkage in the polyester is as aforesaid controlled largely by the amount of unsaturated dibas'ic' a'cid in the polyester available for crosslinkage. About .5% to 5% is preferred, although the amount of unsaturated -dibasic' 'acid 'm'ay be as much"as25% or even more-of the polyester.

Referring particularly to'the drawing, wherein like parts are designated by-like 'numeralsof' ref erence throughout the several' vi'ewsj abruslrlll, the improvement of which the present invention is concerned, comprises ahandleor hubportion I, which may 'h'avean opening '2 to receivea'sulh' able shaft-or handle, and suitablem'eans, such as one or more locking-rings3 for'retaining on the hub or handle l'the=wirebristles-'4;' which extend out from the hub or"handleportion"(and are generally radially therefron'i in a rotary brush), all in accordance with conventional prac'- tice.

In accordanc'e'with the'pre'sent invention/the spaces 5 between the' bristles 4 are filled with a solid-polymerization product or resin ofth'e class above-described, which-res'i'n-h'as been solidified in situ by molecular'growth or'by polymerization" to substantially completely encloseall'but'the' end portions of the various'wire' filamentsin' a unitary and solidmass.

In the manufacture 'of brushes embodying-the present invention, the brush ni'aybe placed'in' a suitable mold' ll having a'cavity adapted to receive the'conventional wire brushes "and being of such size that the bristles preferably bear against the wall of the cavity." The mold may have a lower'portion I3 and a suitable cover l4; together with means such as lugs l5 and the nut lfiffor fastening thecover 14 to the lower portion of the mold. A suitable gasket l1 maybe applied on either side of the surface of the hub to form' a seal and to prevent'liquid from entering intothe'space'Z adapted to receive the shaft. Suitable means, such as the spaced collars [Band the bolt l 9, maybe provided for applying-pressure to seal the space between the external surfaceof the hub I and the parts of the mold.-

After the conventional wire "brush is incor-' porated in the mold and the mold sealed so thatleakage is prevented into the shaft portion thereof, a fluid polymerizable composition as-above-' described andcontaining a-suitable polymerization catalyst is poured through'theopeningor sprue hole 20 to completely surround and en velop all of the bristles. A vent 2| may be pro-'" vided' to enable escape of air from the moldl After the mold has been filled with-fluid composition capable of being"'polymerized or solidifiedto the solid state, the fluid-composition is con-- verted by molecular-growthto the solid-state,- eitherby allowing .it to set atnormal temperatures until polymerization has occurred, or by heating it at slightly elevated temperatures.

The rate of polymerization is controlled by the catalyst incorporated in the composition. The higher the percentage of oxidation catalyst, such as organic soluble peroxide, for example benzoyl peroxide, tertiary butyl hydrogen peroxide, or any other suitable catalyst, the greater is the rate at which hardening occurs. The amount of catalyst preferably should not be greater than .5% of the weight of the polymerizable constituents and as little as 01% is quite effective, all as well-known to those skilled in this art.

In order to remove the solidified brush from the mold, the inner mold surface should preferably be coated prior to incorporation of the brush therein with a suitable lubricating material, such for example as a cellulose acetate.

The following example illustrates the present invention:

A liquid polyester is prepared by heating 1.05 mols of diethylene glycol with .7 mol of adipic acid and .3 mol of maleic anhydride. While stirring in a vessel equipped with a reflux condenser, cooled by fluid maintained at a temperature of about 105 C. to permit escape of water vapor but to return higher boiling constituents to the reaction mixture, the mixture is heated sufficiently to maintain boiling conditions until the temperature reaches 225 0., whereupon the reaction mixture is allowed to cool. About parts of the cooled reaction mixture is mixed with 45 parts by weight of styrene and .1 part of tertitary butyl hydroperoxide.

A conventional Wire brush having bristles radially extending from the hub is incorporated in the cavity of the mold H, which was coated throughout with a layer of cellulose acetate or any other suitable mold lubricant. In the mold the hub l bears against the gasket l7 and the external edges 26 of the bristles bear against the inner wall portion 25a. The fluid solidifiable composition is poured through the opening 20 until it rises within the vent 2|. It is allowed to remain at C. until it has completely solidified. The brush removed from the mold has exceptionally desirable properties. It has much more rapid cutting time and much superior life than any wire brushes of which I am aware.

As aforepointed out, the condensation resinous materials, and particularly those of the polyester mono-olefinic type, such for example as the linear polyester of one or more dihydric alcohols and one or more dibasic acids, part of which may or may not be unsaturated, with a mono-olefinic compound such as styrene, give by far the most desirable properties. This is particularly true when the percentage of polyester is greater than the percentage of mono-olefinic compound. Mixtures of mono-olefinic compounds such as styrene, methyl acrylate, methyl methacrylate, may be used for one alone. Similarly, mixtures of polyhydric alcohols, such as ethylene glycol and/or glycerol with a polyethylene glycol may be used in place of one alone, and a single dicarboxylic acid or a mixture of several may be used, providing the mono-olefinic compound is compatible with the resultant liquid or viscous condensation product.

Although the invention may be employed in various ways, only preferred embodiments have been illustrated and described. Other embodi- 6 ments may be made within the invention as provided by the patent statutes.

What I claim is:

1. In a wire brush comprising a fastening portion and a plurality of wire bristles extending therefrom, the improvement which comprises a solid polymerization product of a mixture of a polyester of at least one compound selected from the group consisting of dibasic acids and dibasic acid anhydrides and at least one polyhydric a1- cohol and a mono-olefinic compound compatible and polymerizable therewith substantially completely surrounding and reinforcing the sides of said wire bristles and joining portions spaced from said fastening portion together.

2. In a wire brush comprising a hub portion adapted to receive a shaft and a plurality of wire bristles extending in a general radial direction therefrom, the improvement which comprises a solid polymerization product of polyester of at least one compound selected from the group consisting of dibasic acids and dibasic acid anhydrides and at least one polyhydric alcohol and compatible mono-olefinic compound entirely surrounding said bristles and integrally bonding portions of said bristles radially spaced from said hub.

3. In a wire brush comprising a hub portion adapted to receive a shaft and a plurality of wire bristles extending in a general radial direction therefrom, the improvement which comprises a solid polymerization product of a mixture of styrene and an unsaturated condensation product of at least one dibasic acid and at least one di- F hydric alcohol entirely surrounding said bristles and integrally bonding portions of said bristles radially spaced from said hub.

4. In a wire brush comprising a hub portion adapted to receive a shaft and a plurality of wire bristles extending in a general radia1 direction therefrom, the improvement which comprises a solid polymerization product of a mixture of a monoolefinic compound polymerizable and compatible with an unsaturated condensation prod uct of at least one dibasic acid, and at least one dihydric alcohol entirely surrounding said bristles and integrally bonding portions of said bristles radially spaced from said hub.

5. In a wire brush comprising a hub portion adapted to receive a shaft and a plurality of wire bristles extending in a general radial direction therefrom, the improvement which comprises a solid polymerization product of a mixture of styrene and a fluid condensation product of a dihydric alcohol, an alpha-beta unsaturated dicarboxylic acid, and a saturated dicarboxylic acid entirely surrounding said bristles and integrally bonding portions of said bristles radially spaced from said hub.

GILBERT H. SWART.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,308,330 Brown July 1, 1919 1,764,662 Tomlin June 17, 1930 2,130,948 Carothers Sept. 20, 1938 2,207,158 Neville July 9, 1940 2,390,437 Hayes Dec. 4, 1945 2,397,471 Cox Apr. 2, 1946 2,413,219 DAlelio Dec. 24, 1946 2,426,315 Marick Aug. 26, 1947 

